Researchers investigate ‘supernatural’ cave in Finland

Shamans in Finland have used Pirunkirkko to communicate with spirits for hundreds of years. Now, researchers have studied the cave and what might have made this special place chosen for spiritual communication.

Koli National Park is a large green area that includes a mountain of the same name. The mountain is 347 meters above sea level and consists mostly of white quartz. From a geological point of view, this is the oldest land you can walk on in Europe. In the national park there is also a cave called “Devil’s Church” or Pirunkirkko in Finnish. The cave is 34 meters long.

Pirunkirkko is known for mysterious sounds coming from inside the cave and has long been an important place for shamans to contact the spirit world. Even today the cave is an important place in shamanism.

However, the sounds produced in the cave have long been unexplained, but now researchers from the University of Helsinki and the University of Eastern Finland have investigated the acoustics, and the results have been published in De Gruyter Open Access.

Magic rituals

The researchers began by going through historical archives that contained information about several shamans and healers who worked in the area. One of them was a man named Kinolainen, who used the cave for magical rituals in the mid-18th century.

– According to folklore, Kinolainen took his patients to the “church” to talk to the devil about the causes and cures for their ailments. This kind of healing ritual often involved loud screaming, stamping, shooting and banging, said University of Helsinki archaeologist Riitta Rainio, according to popular science magazine Världens Historia.

It is said that a vicar named the cave the “Devil’s Church” after seeing a boulder next to the cave that resembled a pulpit.

In addition, a modern practitioner of shamanism was interviewed who now uses the cave for rituals. He believes that there is a special energy connected to the surrounding nature.

Resonance phenomenon

After taking acoustic measurements in the cave, the researchers found that the sounds coming from the cave are a so-called resonance phenomenon. The phenomenon is said to be caused by a standing wave between the parallel, smooth walls that produces a sound at the cave’s natural frequency of 231 Hz. So if someone is drumming, clapping or singing, for example, the sounds will propagate and create a louder and longer acoustic reverberation in the cave.

– We recorded the shamanic practitioners and found that they repeatedly produced sounds at 231 Hz, which were then amplified by the cave at its natural frequency, says Rainio.

Resonance is common in small spaces, but it is particularly rare in nature because it requires very specific conditions that are rarely met in natural formations, as it requires smooth, solid and parallel surfaces. However, similar resonances have been measured in stone age caves in France and Spain, often near cave paintings.